You need an NTFS partition: Windows NT, 2000 and both XP editions support NTFS. You may well have XP home/pro as a FAT32 partiton but you can convert it (use windows help and search for the convert command). You will only see the security tab on an NTFS partition. If you do have XP (or Windows 2000) on an NTFS partition then experiment with the security settings (when you right-click a folder/file and select properties) to lock people out. The best thing to use is file encryption (search windows help for EFS)